A conventional retaining member included in an electric component is partially deformed by elastic force and inserted into an opening in a substrate, and the electric component is retained on the substrate by reactive force or restoring force generated by the deformation of the retaining member. For example, JP-A-2007-128772 discloses that a metal plate is punched out in a die cutting process, and then, pressure is applied to the metal plate and the metal plate is bent so that the retaining member is formed. A pair of first leg portions extends in the same direction from a flat plate-like base portion. A spring portion of the first leg portion is deformed elastically and inserted into an opening of the substrate in the plate thickness direction with a coupling portion between the spring portion and a parallel portion as a fulcrum point. The plate thickness direction is a direction substantially perpendicular to the substrate thickness and an inward direction in the opening. Then, the spring portion contacts a side wall of the opening by reactive force to the deformation, and thereby, pulling out of the electric component from the substrate is suppressed. By using the above-mentioned retaining structure, an occupied space of the electric component on the substrate can be reduced, and the number of assembling steps can be decreased compared to combining by screws.
In the retaining member of JP-A-2007-128772, the spring portion contacts the side wall of the opening by reactive force itself with respect to the elastic deformation, and the electric component is retained on the substrate. Thus, bearing force with respect to external force or tensile for pulling the spring portion from the opening is low. That is, retaining strength of the electric component to the substrate is low and the electric component is pulled out from the substrate easily.
In general, a metal coating layer is formed over the side wall of the opening. However, when bearing force with respect to tensile is improved, since reaction force having spring property with respect to the elastic deformation of the spring portion may increase, the metal coating layer is easily peeled off. That is, the side wall of the opening is easily damaged.